Remove unused group filter

app/views/groups/_filter.html.haml

-= form_tag group_filter_path(entity), method: 'get' do
-  %fieldset
-    %ul.nav.nav-pills.nav-stacked
-      %li{class: ("active" if !params[:status])}
-        = link_to group_filter_path(entity, status: nil) do
-          Open
-      %li{class: ("active" if params[:status] == 'closed')}
-        = link_to group_filter_path(entity, status: 'closed') do
-          Closed
-      %li{class: ("active" if params[:status] == 'all')}
-        = link_to group_filter_path(entity, status: 'all') do
-          All
-
-  %fieldset
-    %legend Projects:
-    %ul.nav.nav-pills.nav-stacked
-      - @projects.each do |project|
-        - unless entities_per_project(project, entity).zero?
-          %li{class: ("active" if params[:project_id] == project.id.to_s)}
-            = link_to group_filter_path(entity, project_id: project.id) do
-              = project.name_with_namespace
-              %small.pull-right= entities_per_project(project, entity)
-      - if @projects.blank?
-        .nothing-here-block This group has no projects yet
-
-  %fieldset
-    %hr
-    = link_to "Reset", group_filter_path(entity), class: 'btn pull-right'
-